BEARING SHAFT AND BEARING
First Claim
1. A bearing shaft provided with an outer peripheral surface that includes a raceway surface on which a rolling element rolls,the bearing shaft being made of steel containing carbon of 0.7% or more,the raceway surface being formed with a nitrogen-enriched layer, andthe absolute value of compressive residual stress in the surface of the nitrogen-enriched layer being 600 MPa or more and 1700 MPa or less.
1 Assignment
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Accused Products
Abstract
The present invention relates to a bearing shaft provided with an outer peripheral surface that includes a raceway surface (side surface) on which a rolling element rolls. The bearing shaft is made of steel containing carbon of 0.7% or more. The raceway surface is formed with a nitrogen-enriched layer. The absolute value of compressive residual stress in the surface of the nitrogen-enriched layer (i.e., the surface of a hardened layer which is formed on the side surface of the bearing shaft by shot peening) is 600 MPa or more and 1700 MPa or less. Thereby, it is possible for the present invention to prolong the operation life of a bearing.
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Citations
12 Claims
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1. A bearing shaft provided with an outer peripheral surface that includes a raceway surface on which a rolling element rolls,
the bearing shaft being made of steel containing carbon of 0.7% or more, the raceway surface being formed with a nitrogen-enriched layer, and the absolute value of compressive residual stress in the surface of the nitrogen-enriched layer being 600 MPa or more and 1700 MPa or less.
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6. A bearing comprising a bearing shaft provided with an outer peripheral surface that includes a raceway surface, and a rolling element that has a surface in contact with the raceway surface,
the bearing shaft being made of steel containing carbon of 0.7% or more, the raceway surface being formed with a nitrogen-enriched layer, the absolute value of compressive residual stress in the surface of the nitrogen-enriched layer being 600 MPa or more and 1700 MPa or less, and the amount of residual austenite in an outer portion of the surface of the rolling element being greater than the amount of residual austenite in an outer portion of the nitrogen-enriched layer formed on the raceway surface of the bearing shaft.
Specification